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// Inferno utils/5l/asm.c
// https://bitbucket.org/inferno-os/inferno-os/src/master/utils/5l/asm.c
//
// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
// Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
// Portions Copyright © 1997-1999 Vita Nuova Limited
// Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
// Portions Copyright © 2004,2006 Bruce Ellis
// Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
// Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
// Portions Copyright © 2009 The Go Authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package arm
import (
"cmd/internal/objabi"
"cmd/internal/sys"
"cmd/link/internal/ld"
"cmd/link/internal/loader"
"cmd/link/internal/sym"
"debug/elf"
"fmt"
"log"
)
// This assembler:
//
// .align 2
// local.dso_init:
// ldr r0, .Lmoduledata
// .Lloadfrom:
// ldr r0, [r0]
// b runtime.addmoduledata@plt
// .align 2
// .Lmoduledata:
// .word local.moduledata(GOT_PREL) + (. - (.Lloadfrom + 4))
// assembles to:
//
// 00000000 <local.dso_init>:
// 0: e59f0004 ldr r0, [pc, #4] ; c <local.dso_init+0xc>
// 4: e5900000 ldr r0, [r0]
// 8: eafffffe b 0 <runtime.addmoduledata>
// 8: R_ARM_JUMP24 runtime.addmoduledata
// c: 00000004 .word 0x00000004
// c: R_ARM_GOT_PREL local.moduledata
func gentext(ctxt *ld.Link, ldr *loader.Loader) {
initfunc, addmoduledata := ld.PrepareAddmoduledata(ctxt)
if initfunc == nil {
return
}
o := func(op uint32) {
initfunc.AddUint32(ctxt.Arch, op)
}
o(0xe59f0004)
o(0xe08f0000)
o(0xeafffffe)
rel, _ := initfunc.AddRel(objabi.R_CALLARM)
rel.SetOff(8)
rel.SetSiz(4)
rel.SetSym(addmoduledata)
rel.SetAdd(0xeafffffe) // vomit
o(0x00000000)
rel2, _ := initfunc.AddRel(objabi.R_PCREL)
rel2.SetOff(12)
rel2.SetSiz(4)
rel2.SetSym(ctxt.Moduledata)
rel2.SetAdd(4)
}
// Preserve highest 8 bits of a, and do addition to lower 24-bit
// of a and b; used to adjust ARM branch instruction's target
func braddoff(a int32, b int32) int32 {
return int32((uint32(a))&0xff000000 | 0x00ffffff&uint32(a+b))
}
func adddynrel(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym, r loader.Reloc, rIdx int) bool {
targ := r.Sym()
var targType sym.SymKind
if targ != 0 {
targType = ldr.SymType(targ)
}
switch r.Type() {
default:
if r.Type() >= objabi.ElfRelocOffset {
ldr.Errorf(s, "unexpected relocation type %d (%s)", r.Type(), sym.RelocName(target.Arch, r.Type()))
return false
}
// Handle relocations found in ELF object files.
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_PLT32):
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_CALLARM)
if targType == sym.SDYNIMPORT {
addpltsym(target, ldr, syms, targ)
su.SetRelocSym(rIdx, syms.PLT)
su.SetRelocAdd(rIdx, int64(braddoff(int32(r.Add()), ldr.SymPlt(targ)/4)))
}
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_THM_PC22): // R_ARM_THM_CALL
ld.Exitf("R_ARM_THM_CALL, are you using -marm?")
return false
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_GOT32): // R_ARM_GOT_BREL
if targType != sym.SDYNIMPORT {
addgotsyminternal(target, ldr, syms, targ)
} else {
ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_ARM_GLOB_DAT))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_CONST) // write r->add during relocsym
su.SetRelocSym(rIdx, 0)
su.SetRelocAdd(rIdx, r.Add()+int64(ldr.SymGot(targ)))
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_GOT_PREL): // GOT(nil) + A - nil
if targType != sym.SDYNIMPORT {
addgotsyminternal(target, ldr, syms, targ)
} else {
ld.AddGotSym(target, ldr, syms, targ, uint32(elf.R_ARM_GLOB_DAT))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_PCREL)
su.SetRelocSym(rIdx, syms.GOT)
su.SetRelocAdd(rIdx, r.Add()+4+int64(ldr.SymGot(targ)))
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_GOTOFF): // R_ARM_GOTOFF32
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_GOTOFF)
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_GOTPC): // R_ARM_BASE_PREL
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_PCREL)
su.SetRelocSym(rIdx, syms.GOT)
su.SetRelocAdd(rIdx, r.Add()+4)
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_CALL):
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_CALLARM)
if targType == sym.SDYNIMPORT {
addpltsym(target, ldr, syms, targ)
su.SetRelocSym(rIdx, syms.PLT)
su.SetRelocAdd(rIdx, int64(braddoff(int32(r.Add()), ldr.SymPlt(targ)/4)))
}
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_REL32): // R_ARM_REL32
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_PCREL)
su.SetRelocAdd(rIdx, r.Add()+4)
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_ABS32):
if targType == sym.SDYNIMPORT {
ldr.Errorf(s, "unexpected R_ARM_ABS32 relocation for dynamic symbol %s", ldr.SymName(targ))
}
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_ADDR)
return true
case objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_PC24),
objabi.ElfRelocOffset + objabi.RelocType(elf.R_ARM_JUMP24):
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_CALLARM)
if targType == sym.SDYNIMPORT {
addpltsym(target, ldr, syms, targ)
su.SetRelocSym(rIdx, syms.PLT)
su.SetRelocAdd(rIdx, int64(braddoff(int32(r.Add()), ldr.SymPlt(targ)/4)))
}
return true
}
// Handle references to ELF symbols from our own object files.
if targType != sym.SDYNIMPORT {
return true
}
// Reread the reloc to incorporate any changes in type above.
relocs := ldr.Relocs(s)
r = relocs.At(rIdx)
switch r.Type() {
case objabi.R_CALLARM:
if target.IsExternal() {
// External linker will do this relocation.
return true
}
addpltsym(target, ldr, syms, targ)
su := ldr.MakeSymbolUpdater(s)
su.SetRelocSym(rIdx, syms.PLT)
su.SetRelocAdd(rIdx, int64(braddoff(int32(r.Add()), ldr.SymPlt(targ)/4))) // TODO: don't use r.Add for instruction bytes (issue 19811)
return true
case objabi.R_ADDR:
if ldr.SymType(s) != sym.SDATA {
break
}
if target.IsElf() {
ld.Adddynsym(ldr, target, syms, targ)
rel := ldr.MakeSymbolUpdater(syms.Rel)
rel.AddAddrPlus(target.Arch, s, int64(r.Off()))
rel.AddUint32(target.Arch, elf.R_INFO32(uint32(ldr.SymDynid(targ)), uint32(elf.R_ARM_GLOB_DAT))) // we need a nil + A dynamic reloc
su := ldr.MakeSymbolUpdater(s)
su.SetRelocType(rIdx, objabi.R_CONST) // write r->add during relocsym
su.SetRelocSym(rIdx, 0)
return true
}
}
return false
}
func elfreloc1(ctxt *ld.Link, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, ri int, sectoff int64) bool {
out.Write32(uint32(sectoff))
elfsym := ld.ElfSymForReloc(ctxt, r.Xsym)
siz := r.Size
switch r.Type {
default:
return false
case objabi.R_ADDR, objabi.R_DWARFSECREF:
if siz == 4 {
out.Write32(uint32(elf.R_ARM_ABS32) | uint32(elfsym)<<8)
} else {
return false
}
case objabi.R_PCREL:
if siz == 4 {
out.Write32(uint32(elf.R_ARM_REL32) | uint32(elfsym)<<8)
} else {
return false
}
case objabi.R_CALLARM:
if siz == 4 {
relocs := ldr.Relocs(s)
r := relocs.At(ri)
if r.Add()&0xff000000 == 0xeb000000 { // BL // TODO: using r.Add here is bad (issue 19811)
out.Write32(uint32(elf.R_ARM_CALL) | uint32(elfsym)<<8)
} else {
out.Write32(uint32(elf.R_ARM_JUMP24) | uint32(elfsym)<<8)
}
} else {
return false
}
case objabi.R_TLS_LE:
out.Write32(uint32(elf.R_ARM_TLS_LE32) | uint32(elfsym)<<8)
case objabi.R_TLS_IE:
out.Write32(uint32(elf.R_ARM_TLS_IE32) | uint32(elfsym)<<8)
case objabi.R_GOTPCREL:
if siz == 4 {
out.Write32(uint32(elf.R_ARM_GOT_PREL) | uint32(elfsym)<<8)
} else {
return false
}
}
return true
}
func elfsetupplt(ctxt *ld.Link, plt, got *loader.SymbolBuilder, dynamic loader.Sym) {
if plt.Size() == 0 {
// str lr, [sp, #-4]!
plt.AddUint32(ctxt.Arch, 0xe52de004)
// ldr lr, [pc, #4]
plt.AddUint32(ctxt.Arch, 0xe59fe004)
// add lr, pc, lr
plt.AddUint32(ctxt.Arch, 0xe08fe00e)
// ldr pc, [lr, #8]!
plt.AddUint32(ctxt.Arch, 0xe5bef008)
// .word &GLOBAL_OFFSET_TABLE[0] - .
plt.AddPCRelPlus(ctxt.Arch, got.Sym(), 4)
// the first .plt entry requires 3 .plt.got entries
got.AddUint32(ctxt.Arch, 0)
got.AddUint32(ctxt.Arch, 0)
got.AddUint32(ctxt.Arch, 0)
}
}
func machoreloc1(*sys.Arch, *ld.OutBuf, *loader.Loader, loader.Sym, loader.ExtReloc, int64) bool {
return false
}
func pereloc1(arch *sys.Arch, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, sectoff int64) bool {
rs := r.Xsym
rt := r.Type
if ldr.SymDynid(rs) < 0 {
ldr.Errorf(s, "reloc %d (%s) to non-coff symbol %s type=%d (%s)", rt, sym.RelocName(arch, rt), ldr.SymName(rs), ldr.SymType(rs), ldr.SymType(rs))
return false
}
out.Write32(uint32(sectoff))
out.Write32(uint32(ldr.SymDynid(rs)))
var v uint32
switch rt {
default:
// unsupported relocation type
return false
case objabi.R_DWARFSECREF:
v = ld.IMAGE_REL_ARM_SECREL
case objabi.R_ADDR:
v = ld.IMAGE_REL_ARM_ADDR32
}
out.Write16(uint16(v))
return true
}
// sign extend a 24-bit integer
func signext24(x int64) int32 {
return (int32(x) << 8) >> 8
}
// encode an immediate in ARM's imm12 format. copied from ../../../internal/obj/arm/asm5.go
func immrot(v uint32) uint32 {
for i := 0; i < 16; i++ {
if v&^0xff == 0 {
return uint32(i<<8) | v | 1<<25
}
v = v<<2 | v>>30
}
return 0
}
// Convert the direct jump relocation r to refer to a trampoline if the target is too far
func trampoline(ctxt *ld.Link, ldr *loader.Loader, ri int, rs, s loader.Sym) {
relocs := ldr.Relocs(s)
r := relocs.At(ri)
switch r.Type() {
case objabi.R_CALLARM:
var t int64
// ldr.SymValue(rs) == 0 indicates a cross-package jump to a function that is not yet
// laid out. Conservatively use a trampoline. This should be rare, as we lay out packages
// in dependency order.
if ldr.SymValue(rs) != 0 {
// r.Add is the instruction
// low 24-bit encodes the target address
t = (ldr.SymValue(rs) + int64(signext24(r.Add()&0xffffff)*4) - (ldr.SymValue(s) + int64(r.Off()))) / 4
}
if t > 0x7fffff || t < -0x800000 || ldr.SymValue(rs) == 0 || (*ld.FlagDebugTramp > 1 && ldr.SymPkg(s) != ldr.SymPkg(rs)) {
// direct call too far, need to insert trampoline.
// look up existing trampolines first. if we found one within the range
// of direct call, we can reuse it. otherwise create a new one.
offset := (signext24(r.Add()&0xffffff) + 2) * 4
var tramp loader.Sym
for i := 0; ; i++ {
oName := ldr.SymName(rs)
name := oName + fmt.Sprintf("%+d-tramp%d", offset, i)
tramp = ldr.LookupOrCreateSym(name, int(ldr.SymVersion(rs)))
ldr.SetAttrReachable(tramp, true)
if ldr.SymType(tramp) == sym.SDYNIMPORT {
// don't reuse trampoline defined in other module
continue
}
if oName == "runtime.deferreturn" {
ldr.SetIsDeferReturnTramp(tramp, true)
}
if ldr.SymValue(tramp) == 0 {
// either the trampoline does not exist -- we need to create one,
// or found one the address which is not assigned -- this will be
// laid down immediately after the current function. use this one.
break
}
t = (ldr.SymValue(tramp) - 8 - (ldr.SymValue(s) + int64(r.Off()))) / 4
if t >= -0x800000 && t < 0x7fffff {
// found an existing trampoline that is not too far
// we can just use it
break
}
}
if ldr.SymType(tramp) == 0 {
// trampoline does not exist, create one
trampb := ldr.MakeSymbolUpdater(tramp)
ctxt.AddTramp(trampb)
if ctxt.DynlinkingGo() {
if immrot(uint32(offset)) == 0 {
ctxt.Errorf(s, "odd offset in dynlink direct call: %v+%d", ldr.SymName(rs), offset)
}
gentrampdyn(ctxt.Arch, trampb, rs, int64(offset))
} else if ctxt.BuildMode == ld.BuildModeCArchive || ctxt.BuildMode == ld.BuildModeCShared || ctxt.BuildMode == ld.BuildModePIE {
gentramppic(ctxt.Arch, trampb, rs, int64(offset))
} else {
gentramp(ctxt.Arch, ctxt.LinkMode, ldr, trampb, rs, int64(offset))
}
}
// modify reloc to point to tramp, which will be resolved later
sb := ldr.MakeSymbolUpdater(s)
relocs := sb.Relocs()
r := relocs.At(ri)
r.SetSym(tramp)
r.SetAdd(r.Add()&0xff000000 | 0xfffffe) // clear the offset embedded in the instruction
}
default:
ctxt.Errorf(s, "trampoline called with non-jump reloc: %d (%s)", r.Type(), sym.RelocName(ctxt.Arch, r.Type()))
}
}
// generate a trampoline to target+offset
func gentramp(arch *sys.Arch, linkmode ld.LinkMode, ldr *loader.Loader, tramp *loader.SymbolBuilder, target loader.Sym, offset int64) {
tramp.SetSize(12) // 3 instructions
P := make([]byte, tramp.Size())
t := ldr.SymValue(target) + offset
o1 := uint32(0xe5900000 | 11<<12 | 15<<16) // MOVW (R15), R11 // R15 is actual pc + 8
o2 := uint32(0xe12fff10 | 11) // JMP (R11)
o3 := uint32(t) // WORD $target
arch.ByteOrder.PutUint32(P, o1)
arch.ByteOrder.PutUint32(P[4:], o2)
arch.ByteOrder.PutUint32(P[8:], o3)
tramp.SetData(P)
if linkmode == ld.LinkExternal || ldr.SymValue(target) == 0 {
r, _ := tramp.AddRel(objabi.R_ADDR)
r.SetOff(8)
r.SetSiz(4)
r.SetSym(target)
r.SetAdd(offset)
}
}
// generate a trampoline to target+offset in position independent code
func gentramppic(arch *sys.Arch, tramp *loader.SymbolBuilder, target loader.Sym, offset int64) {
tramp.SetSize(16) // 4 instructions
P := make([]byte, tramp.Size())
o1 := uint32(0xe5900000 | 11<<12 | 15<<16 | 4) // MOVW 4(R15), R11 // R15 is actual pc + 8
o2 := uint32(0xe0800000 | 11<<12 | 15<<16 | 11) // ADD R15, R11, R11
o3 := uint32(0xe12fff10 | 11) // JMP (R11)
o4 := uint32(0) // WORD $(target-pc) // filled in with relocation
arch.ByteOrder.PutUint32(P, o1)
arch.ByteOrder.PutUint32(P[4:], o2)
arch.ByteOrder.PutUint32(P[8:], o3)
arch.ByteOrder.PutUint32(P[12:], o4)
tramp.SetData(P)
r, _ := tramp.AddRel(objabi.R_PCREL)
r.SetOff(12)
r.SetSiz(4)
r.SetSym(target)
r.SetAdd(offset + 4)
}
// generate a trampoline to target+offset in dynlink mode (using GOT)
func gentrampdyn(arch *sys.Arch, tramp *loader.SymbolBuilder, target loader.Sym, offset int64) {
tramp.SetSize(20) // 5 instructions
o1 := uint32(0xe5900000 | 11<<12 | 15<<16 | 8) // MOVW 8(R15), R11 // R15 is actual pc + 8
o2 := uint32(0xe0800000 | 11<<12 | 15<<16 | 11) // ADD R15, R11, R11
o3 := uint32(0xe5900000 | 11<<12 | 11<<16) // MOVW (R11), R11
o4 := uint32(0xe12fff10 | 11) // JMP (R11)
o5 := uint32(0) // WORD $target@GOT // filled in with relocation
o6 := uint32(0)
if offset != 0 {
// insert an instruction to add offset
tramp.SetSize(24) // 6 instructions
o6 = o5
o5 = o4
o4 = 0xe2800000 | 11<<12 | 11<<16 | immrot(uint32(offset)) // ADD $offset, R11, R11
o1 = uint32(0xe5900000 | 11<<12 | 15<<16 | 12) // MOVW 12(R15), R11
}
P := make([]byte, tramp.Size())
arch.ByteOrder.PutUint32(P, o1)
arch.ByteOrder.PutUint32(P[4:], o2)
arch.ByteOrder.PutUint32(P[8:], o3)
arch.ByteOrder.PutUint32(P[12:], o4)
arch.ByteOrder.PutUint32(P[16:], o5)
if offset != 0 {
arch.ByteOrder.PutUint32(P[20:], o6)
}
tramp.SetData(P)
r, _ := tramp.AddRel(objabi.R_GOTPCREL)
r.SetOff(16)
r.SetSiz(4)
r.SetSym(target)
r.SetAdd(8)
if offset != 0 {
// increase reloc offset by 4 as we inserted an ADD instruction
r.SetOff(20)
r.SetAdd(12)
}
}
func archreloc(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, r loader.Reloc, s loader.Sym, val int64) (o int64, nExtReloc int, ok bool) {
rs := r.Sym()
rs = ldr.ResolveABIAlias(rs)
if target.IsExternal() {
switch r.Type() {
case objabi.R_CALLARM:
// set up addend for eventual relocation via outer symbol.
_, off := ld.FoldSubSymbolOffset(ldr, rs)
xadd := int64(signext24(r.Add()&0xffffff))*4 + off
if xadd/4 > 0x7fffff || xadd/4 < -0x800000 {
ldr.Errorf(s, "direct call too far %d", xadd/4)
}
return int64(braddoff(int32(0xff000000&uint32(r.Add())), int32(0xffffff&uint32(xadd/4)))), 1, true
}
return -1, 0, false
}
const isOk = true
const noExtReloc = 0
switch r.Type() {
// The following three arch specific relocations are only for generation of
// Linux/ARM ELF's PLT entry (3 assembler instruction)
case objabi.R_PLT0: // add ip, pc, #0xXX00000
if ldr.SymValue(syms.GOTPLT) < ldr.SymValue(syms.PLT) {
ldr.Errorf(s, ".got.plt should be placed after .plt section.")
}
return 0xe28fc600 + (0xff & (int64(uint32(ldr.SymValue(rs)-(ldr.SymValue(syms.PLT)+int64(r.Off()))+r.Add())) >> 20)), noExtReloc, isOk
case objabi.R_PLT1: // add ip, ip, #0xYY000
return 0xe28cca00 + (0xff & (int64(uint32(ldr.SymValue(rs)-(ldr.SymValue(syms.PLT)+int64(r.Off()))+r.Add()+4)) >> 12)), noExtReloc, isOk
case objabi.R_PLT2: // ldr pc, [ip, #0xZZZ]!
return 0xe5bcf000 + (0xfff & int64(uint32(ldr.SymValue(rs)-(ldr.SymValue(syms.PLT)+int64(r.Off()))+r.Add()+8))), noExtReloc, isOk
case objabi.R_CALLARM: // bl XXXXXX or b YYYYYY
// r.Add is the instruction
// low 24-bit encodes the target address
t := (ldr.SymValue(rs) + int64(signext24(r.Add()&0xffffff)*4) - (ldr.SymValue(s) + int64(r.Off()))) / 4
if t > 0x7fffff || t < -0x800000 {
ldr.Errorf(s, "direct call too far: %s %x", ldr.SymName(rs), t)
}
return int64(braddoff(int32(0xff000000&uint32(r.Add())), int32(0xffffff&t))), noExtReloc, isOk
}
return val, 0, false
}
func archrelocvariant(*ld.Target, *loader.Loader, loader.Reloc, sym.RelocVariant, loader.Sym, int64) int64 {
log.Fatalf("unexpected relocation variant")
return -1
}
func extreloc(target *ld.Target, ldr *loader.Loader, r loader.Reloc, s loader.Sym) (loader.ExtReloc, bool) {
rs := ldr.ResolveABIAlias(r.Sym())
var rr loader.ExtReloc
switch r.Type() {
case objabi.R_CALLARM:
// set up addend for eventual relocation via outer symbol.
rs, off := ld.FoldSubSymbolOffset(ldr, rs)
rr.Xadd = int64(signext24(r.Add()&0xffffff))*4 + off
rst := ldr.SymType(rs)
if rst != sym.SHOSTOBJ && rst != sym.SDYNIMPORT && rst != sym.SUNDEFEXT && ldr.SymSect(rs) == nil {
ldr.Errorf(s, "missing section for %s", ldr.SymName(rs))
}
rr.Xsym = rs
rr.Type = r.Type()
rr.Size = r.Siz()
return rr, true
}
return rr, false
}
func addpltreloc(ldr *loader.Loader, plt *loader.SymbolBuilder, got *loader.SymbolBuilder, s loader.Sym, typ objabi.RelocType) {
r, _ := plt.AddRel(typ)
r.SetSym(got.Sym())
r.SetOff(int32(plt.Size()))
r.SetSiz(4)
r.SetAdd(int64(ldr.SymGot(s)) - 8)
plt.SetReachable(true)
plt.SetSize(plt.Size() + 4)
plt.Grow(plt.Size())
}
func addpltsym(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym) {
if ldr.SymPlt(s) >= 0 {
return
}
ld.Adddynsym(ldr, target, syms, s)
if target.IsElf() {
plt := ldr.MakeSymbolUpdater(syms.PLT)
got := ldr.MakeSymbolUpdater(syms.GOTPLT)
rel := ldr.MakeSymbolUpdater(syms.RelPLT)
if plt.Size() == 0 {
panic("plt is not set up")
}
// .got entry
ldr.SetGot(s, int32(got.Size()))
// In theory, all GOT should point to the first PLT entry,
// Linux/ARM's dynamic linker will do that for us, but FreeBSD/ARM's
// dynamic linker won't, so we'd better do it ourselves.
got.AddAddrPlus(target.Arch, plt.Sym(), 0)
// .plt entry, this depends on the .got entry
ldr.SetPlt(s, int32(plt.Size()))
addpltreloc(ldr, plt, got, s, objabi.R_PLT0) // add lr, pc, #0xXX00000
addpltreloc(ldr, plt, got, s, objabi.R_PLT1) // add lr, lr, #0xYY000
addpltreloc(ldr, plt, got, s, objabi.R_PLT2) // ldr pc, [lr, #0xZZZ]!
// rel
rel.AddAddrPlus(target.Arch, got.Sym(), int64(ldr.SymGot(s)))
rel.AddUint32(target.Arch, elf.R_INFO32(uint32(ldr.SymDynid(s)), uint32(elf.R_ARM_JUMP_SLOT)))
} else {
ldr.Errorf(s, "addpltsym: unsupported binary format")
}
}
func addgotsyminternal(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s loader.Sym) {
if ldr.SymGot(s) >= 0 {
return
}
got := ldr.MakeSymbolUpdater(syms.GOT)
ldr.SetGot(s, int32(got.Size()))
got.AddAddrPlus(target.Arch, s, 0)
if target.IsElf() {
} else {
ldr.Errorf(s, "addgotsyminternal: unsupported binary format")
}
}